A description will be made of a generic header used in a wireless access system.
Also, a brief description will be made of a Media Access Control (MAC) Protocol Data Unit (PDU) used at a MAC layer.
In general, Layer 2 (L2) or its underlying layer, that is, a MAC layer (or a link layer) and a Physical (PHY) layer operate according to different protocols depending on wireless access systems such as Local Area Network (LAN), wireless LAN, 3rd Generation Partnership Project (3GPP)/3GPP2, and wireless Metropolitan Area Network (MAN). Accordingly, a different header format is defined for a MAC PDU in each wireless access system.
FIG. 1 illustrates an exemplary MAC PDU in one of wireless access systems, Institute of Electrical and Electronics Engineers (IEEE) 802.16e.
Referring to FIG. 1, the MAC PDU may include a Generic MAC Header (GMH), Payload, and a Cyclic Redundancy Check (CRC). The GMH, which is used to deliver data between nodes at link layers, may include a MAC address or a link address, a header error check, and link-layer control information.
The Payload carries actual transmission data in the MAC PDU. The CRC refers to a technique for determining a check value to determine whether an error has occurred to the data during data transmission over a network. Although the GMH is mandatory, the Payload and the CRC are optional in the MAC PDU.